Requirements to a package for a medical product are defined in numerous standards. Especially a package for sterile medical products is subjected to strict regulations. In the case of hollow fiber filter modules, for example dialyzers, the standard EN ISO 8637:2014 “Cardiovascular implants and extracorporeal systems—hemodialyzers, hemodiafilters, hemofilters and hemoconcentrators” is especially important and has to be complied with. With respect to the sterility of packaged hollow fiber filter modules, this standard defines the fact that blood-conveying parts of the apparatus have to be sterile and consequently have to be properly packaged. Related to a hollow fiber filter module such as a dialyzer, this means that the blood compartment of the module has to be sterile, whereas the dialysate compartment is subjected to less strict requirements.
For sterilizing packaged hollow fiber filter modules the use of gamma rays within the scope of radiation is generally known. Gamma ray sterilization takes place in the absence of oxygen so as to avoid oxidative material stress both of the packaged hollow fiber filter module and of the package used for this purpose during sterilization. In known sterile containers for hollow fiber filter modules one module at a time is packaged together with one oxygen absorber in a primary package hermetically sealed against the ambience. The oxygen absorber is put into the primary package (special package consisting of polyamide and polyethylene), thus causing oxygen to be almost completely removed from the medical product and from the interior of the package. Around the oxygen absorber and the packaged hollow fiber filter module, the primary package forms a hermetically sealed envelope surrounding and defining a holding volume in which almost no oxygen is present any more as a result of the oxygen absorption. In this condition, the sterilization by means of gamma radiation takes place. A plurality of primary-packaged and sterilized units, for example a lot size of 20, then is accommodated in a secondary package. It can be stated that the secondary package then contains 20 tightly packaged and sterile hollow fiber filter modules (dialyzers). The primary package defines the volume to be sterilized during sterilization and thus forms a sterile barrier which represents the barrier between a sterile and a non-sterile compartment.
The afore-described concept according to prior art involves great challenges: On the one hand, it has to be ensured that before and during sterilization the volume to be sterilized is free from oxygen. On the other hand, it has to be ensured that after sterile packaging, during transport and during the entire storage (usually up to 3 years) of the containers up to the ultimate use the sterility of the hollow fiber filter module is safeguarded. In the afore-described known sterile containers it is a drawback that by improper transport and/or storage the sensitive primary package can be minimally perforated, for example when the primary packages including the filter modules accommodated therein are rubbing against each other in a secondary package. Perforation of the primary package prior to sterilization may result in the fact that oxygen diffuses from outside into the package and is present during sterilization. In this way, the material can be stressed by oxidation. In the case of perforation after sterilization a non-sterility may occur inside the holding volume of the primary package and thus of the dialysate compartment of the filter module. It is another drawback of known packaging concepts that an additional oxygen absorber always has to be added to each individual filter module packaged in a primary package.
Other packaging concepts are known, for example by means of deep-drawn packages made from a strong special film adapting to the shape of a filter module or using alternative films available on the market. Another known solution in which sterilization is equally performed by means of radiation with gamma rays makes use of a tight aluminum-coated package. A drawback in these concepts consists in high cost and production expenditure.
Based on the afore-described prior art, the object underlying the present invention is to eliminate the afore-listed drawbacks, especially to provide a technical concept by which the risk of perforation of the sterile barrier by improper transport and storage can be reduced and thus the sterility of the product can be ensured even in the case of improper transport and/or improper storage.